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A184895 a(n) = (7^n/n!^2) * Product_{k=0..n-1} (14k+1)*(14k+6). 7
1, 42, 22050, 16909900, 15269639700, 15109613875944, 15853342647837688, 17325438750851187600, 19510609713302293636050, 22482485054570487449402900, 26382746561837375612125315092, 31419888802098260334367621118904 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..100

FORMULA

Self-convolution yields Sum_{k=0..n} a(n-k)*a(k) = A184896(n) where A184896(n) = C(2n,n) * (7^n/n!^2)*Product_{k=0..n-1} (7k+1)*(7k+6).

EXAMPLE

G.f.: A(x) = 1 + 42*x + 22050*x^2 + 16909900*x^3 +...

A(x)^2 = 1 + 84*x + 45864*x^2 + 35672000*x^3 +...+ A184896(n)*x^n +...

MATHEMATICA

FullSimplify[Table[2^(2*n) * 7^(3*n) * Gamma[n+1/14] * Gamma[n+3/7] / (Gamma[3/7] * Gamma[1/14] * Gamma[n+1]^2), {n, 0, 15}]] (* Vaclav Kotesovec, Jul 03 2014 *)

PROG

(PARI) {a(n)=(7^n/n!^2)*prod(k=0, n-1, (14*k+1)*(14*k+6))}

CROSSREFS

Cf. A184896; variants: A184424, A178529, A184891, A092870, A184897.

Sequence in context: A095423 A174766 A265191 * A263058 A299503 A159433

Adjacent sequences:  A184892 A184893 A184894 * A184896 A184897 A184898

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jan 25 2011

STATUS

approved

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Last modified May 8 12:57 EDT 2021. Contains 343666 sequences. (Running on oeis4.)